cartopy data ratio requires draw (#61)

* cartopy data ratio requires draw

* call draw

* changelog

Author: mathause

CHANGELOG.md

@@ -8,6 +8,8 @@
 
 ### Bug fixes
 
+- Fixed a bug in `set_map_layout`: the data ratio of a cartopy `GeoAxesSubplot` requires
+  a `draw` to be correct ([#61](https://github.com/mathause/mplotutils/pull/61)).
 - Fix a regression introduced in [#33](https://github.com/mathause/mplotutils/pull/33):
   `cyclic_dataarray` now correctly extrapolates the coordinates
   ([#58](https://github.com/mathause/mplotutils/pull/58)).

mplotutils/map_layout.py

@@ -40,6 +40,9 @@ def set_map_layout(axes, width=17.0, *, nrow=None, ncol=None):
     # read figure data
     f = ax.get_figure()
 
+    # getting the correct data ratio of geoaxes requires draw
+    f.canvas.draw()
+
     bottom = f.subplotpars.bottom
     top = f.subplotpars.top
     left = f.subplotpars.left

mplotutils/tests/test_set_map_layout.py

@@ -195,3 +195,20 @@ def test_set_map_layout_nrow_ncol_only_one_raises():
 
     with pytest.raises(ValueError, match="Must set none or both of 'nrow' and 'ncol'"):
         set_map_layout(None, width=17.0, nrow=None, ncol=1)
+
+
+def test_set_map_layout_cartopy_2_2():
+
+    import cartopy.crs as ccrs
+
+    subplot_kw = {"projection": ccrs.PlateCarree()}
+    with subplots_context(2, 2, subplot_kw=subplot_kw) as (f, axs):
+
+        f.subplots_adjust(hspace=0, wspace=0, top=1, bottom=0, left=0, right=1)
+
+        set_map_layout(axs, width=17)  # width is in cm
+
+        result = f.get_size_inches() * 2.54
+        expected = (17, 8.5)
+
+        np.testing.assert_allclose(result, expected)